Schionning 38' motorsailer Catamaran:14kts on twin 75hp.

Discussion in 'Motorsailers' started by rustybarge, Jun 5, 2014.

  1. Richard Woods
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    Richard Woods Woods Designs

    My equivalent design (but not a motorsailer) is the Transit 38. It weighs 6.5T in the water in day sailing trim. Huge interior.

    I spent a winter cruising one to the Bahamas which was home finished in Virginia using mouldings containered over from the UK. We never had good sailing weather, so our top speed under sail was around 15 knots, no slamming. But others Transits have gone faster

    You can build one from a kit of parts, which starts at GBP25,000. Make the GBP60,000 less of a deal.

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  2. groper
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    groper Senior Member

    The weight is legit - its because they are built from DUFLEX - a pre manufactured balsa core sandwich panel. The panels are CNC routed to patterns and joined together via epoxy adhesive bonded Z-joints. Its a well proven system that is one of the most modern methods in use to build 1 off custom yachts. It produces very light weight structures compared to alot of other methods.

    Totally different ballgame to solid glass molded boat building systems - much heavier...

    As performance is directly related to displacement length ratio more than any other design parameter, the math takes care of itself and the figures dont lie...
     
  3. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    ...is the low weight because they are using vacuum bagged balsa cored panels in the construction? I have heard it mentioned on some home build forums that the joint between the panels weighs more than the panel itself, not sure if it's true though.

    What's the ride like in your boat at 15kts in a lumpy sea?....would the schionning be able to motor at 15kts in steep waves, or would the ride be unbearable?

    I agree with your proposal re outboards, two Yamaha 70 hp OB only weigh 240 kg versus 500 kg for the diesel inboards, a big big saving in weight.
     
  4. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.


    That looks likes a very nice boat.

    I just noticed on the schionning site that the difference between the ordinary sailing Cat and the motorsailer is an extra flat section which is glued over the the original aft section to give the flat planing surface........they supply a standard sailing hull form, and you glue the extra piece over it. ( not sure if you cut out the round bilge piece, or leave it in place)

    That would make a very easy way to adapt any Cat to a planing hull form.....
     
  5. philSweet
    Joined: May 2008
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    philSweet Senior Member

    First, I apologize for the double post. I deleted the first one. It was a draft that contained some rubbish that got posted by mistake.

    My contention isn't that you can't build a 13k pound 38' catamaran. It is only that it doesn't make sense to me to try to put 3 queen cabins into it. I figure each person you berth in a cabin adds about one ton to displacement for cruising. So start with a peopleless boat, then add a ton for each person. If you have three cabins, that implies six tons additional displacement just for the people. For a cruising monohull, you start with about 14K pounds for the peopleless boat. Additional services - laundry, ac, fridge, microwave, watermaker, icemaker, dive compressor, maintenance bench, propulsion space, fuel tankage, pumps, can push that up over 20K. Then add a ton per cabin berth.

    Richards' example of the Transit 38 at 6.5 ton daysailor is in line with this. Add the additional stuff for cruising six and you are at least up to 18K. Maybe I'm having a problem with what you are calling a cabin? Can six adult people change their clothes at the same time standing on the floor without elbowing each other?
     
  6. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    Have a look at this video, start at about 4.30 for the interior shots, its a bit jerky and the camera could be wider angle but should give you an idea.

    https://www.youtube.com/watch?v=NP9kgfi3q2A

    The forward std bunk is the smallest, it's only 5ft wide at the head and 4ft at the foot. Good sitting headroom over it though

    We sailed this boat from Jaynes marine N Chesapeake, to the Bahamas for four months, with up to 5 people on board. It was then sold and is now en route to Alaska

    see here (scroll well down)

    http://www.sailingcatamarans.com/in...ee-transit-strike-16-strike-18-skoota-sagitta

    and more here

    http://www.sailingcatamarans.com/in...ng-flica-wizard-surfsong-eclipse-gwahir-janus

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  7. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    That's what Pat Patterson did with his Twins 28 powercat back in 1989...

    Richard Woods
     

  8. groper
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    groper Senior Member

    Again, your being a little presumptuous ... I happen to have recently purchased a 39ft motor sailor catamaran built from duflex. It has 3 queen berths and 2 saildrive diesels. The ready to sail displacement is 4.5 tonnes.

    Budgeting 1 tonne for each person thereafter is ridiculous ... I'm sure some people might drag that along with them but certainly not normal here in Australia aboard a cat. If you need that much weight carrying capacity then a monohull is probably a better choice for those...
     
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